Area Forecast Discussion
Issued by NWS St. Louis, MO

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KLSX 150505
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1105 PM CST Sat Jan 14 2017

.UPDATE...
Issued at 819 PM CST Sat Jan 14 2017

Next batch of freezing rain moving through southwest MO this
evening. Even a few lightning strikes in this area of
precipitation. Looking at the latest radar loops and HRRR model
runs it appears that this precipitation will move into parts of
central and southeast MO by late evening, then impact areas along
and south of I-70 overnight. Until this area of mainly freezing
rain moves in later tonight there will be patchy fog and freezing
drizzle.

GKS

&&

.SYNOPSIS...
Issued at 254 PM CST Sat Jan 14 2017

No changes to current headlines with ice storm warnings continuing
into Sunday. Next main wave of precipitation/freezing rain
spreads into the area after midnight and impacts the region
through Sunday morning, diminishing Sunday afternoon. Additional
ice accumulations generally 0.10-.20 with localized area near 0.25
inches.

&&

.SHORT TERM...  (Through Late Sunday Afternoon)
Issued at 254 PM CST Sat Jan 14 2017

Focus thru this period continues to be the impending icing event.

Ongoing rain will continue across extreme srn portions of the CWA
thru this afternoon. Can not rule out a passing shower this evening
across this region, but believe much of the evening will remain dry.

A s/w currently over nrn TX/wrn OK region is progd to lift enewd
today and tonight. This is expected to spread precip into the area,
mainly after Midnight tonight. However, mdls depict enuf forcing to
indicate some light precip ahead of the s/w. After the first wave of
precip pushes thru the area Sun morning, precip shud refocus across
nrn and into central portions of the CWA.

As for temps, expect temps to drop a degree or two across the region
after sunset. Temps shud remain fairly steady overnight and may
actually rise a degree or so with onset of precip. Temps shud slowly
rise late Sun morning into the afternoon. Expect most of the CWA to
be aoa the freezing mark by 21z Sun, except far northern MO and
west central IL.

Given the temps expected thru Sun, may see an additional tenth or
two of ice accumulation at any given spot thru the period.

Tilly

.LONG TERM...  (Sunday Night through Next Saturday)
Issued at 254 PM CST Sat Jan 14 2017

The main wave of significant precipitation from Sunday should have
shifted north of the CWA, or be close to exiting north of the CWA at
00Z Monday. In the wake of this wave, an additional precipitation
will be spotty or scattered on Sunday night with the highest
probability across northern MO into central IL. Surface temperatures
will generally be in the 31-33F range across northeast MO/west
central IL during the evening. Overnight however, temps should
uniformly warm above freezing as the surface high pressure dome
continues to retreat eastward from the Great Lakes region, surface
winds slowly veer and increase, and as upper flow exhibits
prounouced backing.

The models have come into better agreement in the Monday/Tuesday time
frame, then diverge some thereafter. The general consensus is the
primary upper low will lift northeastward through the central
Plains on Monday and into the Upper MS Valley on Monday night.
Correspondingly, the accompanying surface low will track into
northwest MO by 00Z Tuesday and into the western Great Lakes
region by Tuesday morning. Deepening and strengthening
south/southwesterly flow aloft and strengthening/veering surface
winds associated with the movement of the aforementioned upper
level and surface systems will transport unseasonably mild air
across the CWA on Monday/Monday evening ahead of the surface low
and advancing cold front. This will not only result in well above
average temps and melting to any residual ice, but will also help
promote enough instability to mention the possibility of embedded
thunderstorms as a band of rain/showers translates across the area
Monday/Monday night. The cold front should completely exit east of
the area by midday Tuesday with weak CAA in its wake and potentially
some "wrap-around" precipitation in northeast MO and west central
IL. The air in the wake of this front however is not all that cold
for January.

Temperatures moderate quickly by Wednesday as a WAA regime becomes
re-established and persists with varying degrees through the
remainder of the week. Temperatures looks to be well above average
Wed-Fri.

Glass

&&

.AVIATION...  (For the 06z TAFs through 06z Sunday Night)
Issued at 1043 PM CST Sat Jan 14 2017

IFR stratus clouds along with fog will continue through the
period at COU and the St Louis metro area with the cigs dropping
into the IFR catagory at UIN as well Sunday morning. Patchy
freezing drizzle can be expected in COU and the St Louis metro
area before another batch of freezing rain across southwest MO
moves northeastward into COU and the St Louis metro area late
tonight/early Sunday morning. Temperatures will warm up enough in
COU and the St Louis metro area to change the freezing rain to
rain early Sunday afternoon. The freezing rain should eventually
make it morthward into UIN by late Sunday morning. Most of the
precipitation will move out of the taf sites by Sunday evening.
Light north-northeast surface wind will veer around to an
easterly direction Sunday afternoon as the surface ridge over the
northern Plains moves eastward into the Ohio valley region.

SPECIFICS FOR KSTL: IFR stratus clouds along with fog will continue
through the period. Patchy drizzle/freezing drizzle can be
expected before another batch of freezing rain across southwest
MO moves northeastward into the STL area late tonight/early
Sunday morning. Temperatures will warm up enough to change the
freezing rain to rain early Sunday afternoon.  Most of the
precipitation will move out of STL by Sunday evening. Light
north surface wind will veer around to an easterly direction
Sunday afternoon as the surface ridge over the northern Plains
moves eastward into the Ohio valley region.

GKS

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Ice Storm Warning until 6 AM CST Sunday for Crawford MO-Iron MO-
     Madison MO-Reynolds MO-Saint Francois MO-Sainte Genevieve
     MO-Washington MO.

     Ice Storm Warning until 3 PM CST Sunday for Audrain MO-Lincoln
     MO-Monroe MO-Pike MO-Ralls MO.

     Ice Storm Warning until noon CST Sunday for Boone MO-Callaway MO-
     Cole MO-Franklin MO-Gasconade MO-Jefferson MO-Moniteau MO-
     Montgomery MO-Osage MO-Saint Charles MO-Saint Louis City MO-
     Saint Louis MO-Warren MO.

     Ice Storm Warning until 6 PM CST Sunday for Knox MO-Lewis MO-
     Marion MO-Shelby MO.

IL...Ice Storm Warning until 6 AM CST Sunday for Randolph IL.

     Ice Storm Warning until 3 PM CST Sunday for Calhoun IL-Greene IL-
     Jersey IL-Macoupin IL-Montgomery IL-Pike IL.

     Ice Storm Warning until noon CST Sunday for Bond IL-Clinton IL-
     Fayette IL-Madison IL-Marion IL-Monroe IL-Saint Clair IL-
     Washington IL.

     Ice Storm Warning until 6 PM CST Sunday for Adams IL-Brown IL.

&&

$$

WFO LSX


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.